Process for producing aluminum using graphite electrodes having reduced wear rates

Abstract

In the production of a metal such as aluminum by electrolysis of an electrolyte bath containing a compound of the metal dissolved therein to produce the metal at a graphite cathode surface, the wear rate of the graphite cathode surface is significantly reduced by incorporating therein selected amounts of certain compounds of aluminum or titanium, especially Al2O3 and TiO2. The improvement is particularly suited to the production of aluminum from chloroaluminate electrolyte baths.

What is claimed is: 
     
       1. A method for the production of metal in an electrolytic cell containing a compound of said metal dissolved in a molten solvent bath, the cell including a plurality of interelectrode spaces between opposed anode and graphite cathode electrode surfaces wherein said bath is moved through a plurality of said interelectrode spaces where said bath is electrolyzed to deposit molten metal on said graphite cathode electrode surfaces wherein the improvement comprises providing said graphite at at least one of said cathode surfaces containing an aluminum compound compatible with the operation of the electrolytic cell and stable for retention of said aluminum in said graphite during cell operation, said graphite being provided by graphitizing at a temperature in the range of over 2000° C. up to 2400° C. carbonaceous material containing an aluminum compound containing 0.1 to 5% aluminum thereby to increase the ash content of said graphite above the content which would be achieved without said aluminum. 
     
     
       2. The method according to claim 1 wherein said graphite is graphitized within the range of 2100° to 2300° C. 
     
     
       3. The method according to claim 1 wherein said aluminum compound is aluminum oxide. 
     
     
       4. The method according to claim 1 wherein said metal produced is aluminum. 
     
     
       5. The method according to claim 4 wherein a titanium compound is also present in said graphite. 
     
     
       6. The method according to claim 4 wherein said bath is moved through said interelectrode space at a velocity of 1-1/2 feet per second or less. 
     
     
       7. The method according to claim 4 wherein said interelectrode space is greater than 1/2 inch. 
     
     
       8. A method for the production of aluminum in an electrolytic cell containing a compound of said aluminum dissolved in a molten solvent bath, the cell including a plurality of interelectrode spaced between opposed anode and graphite cathode electrode surfaces wherein said bath is moved through a plurality of said interelectrode spaces where said bath is electrolyzed to deposit molten aluminum on said graphite cathode electrode surfaces wherein the improvement comprises providing said graphite at at least one of said cathode surfaces by graphitizing at a temperature in the range of over 2000° C. up to 2400° C. carbonaceous material containing 0.2 to 10% Al 2  O 3  thereby to increase the ash content of said graphite above the content which would be achieved without said Al 2  O 3 . 
     
     
       9. The method according to claim 8 wherein said graphite is graphitized within the range of 2100° to 2300° C. 
     
     
       10. The method according to claim 8 wherein a titanium compound is also present in said graphite. 
     
     
       11. The method according to claim 10 wherein said bath is moved through said interelectrode space at a velocity of 1-1/2 feet per second or less. 
     
     
       12. The method according to claim 10 wherein said interelectrode space is greater than 1/2 inch.